Inhibitory Effect of Cinnamaldehyde, Citral, and Eugenol on Aflatoxin Biosynthetic Gene Expression and Aflatoxin B₁ Biosynthesis in Aspergillus flavus

Abstract

In order to reveal the inhibitory effects of cinnamaldehyde, citral, and eugenol on aflatoxin biosynthesis, the expression levels of 5 key aflatoxin biosynthetic genes were evaluated by real-time PCR. Aspergillus flavus growth and AFB1 production were completely inhibited by 0.80 mmol/L of cinnamaldehyde and 2.80 mmol/L of citral. However, at lower concentration, cinnamaldehyde (0.40 mmol/L), eugenol (0.80 mmol/L), and citral (0.56 mmol/L) significantly reduced AFB1 production with inhibition rate of 68.9%, 95.4%, and 41.8%, respectively, while no effect on fungal growth. Real-time PCR showed that the expressions of aflR, aflT, aflD, aflM, and aflP were down-regulated by cinnamaldehyde (0.40 mmol/L), eugenol (0.80 mmol/L), and citral (0.56 mmol/L). In the presence of cinnamaldehyde, AflM was highly down-regulated (average of 5963 folds), followed by aflP, aflR, aflD, and aflT with the average folds of 55, 18, 6.5, and 5.8, respectively. With 0.80 mmol/L of eugenol, aflP was highly down-regulated (average of 2061-folds), followed by aflM, aflR, aflD, and aflT with average of 138-, 15-, 5.2-, and 4.8-folds reduction, respectively. With 0.56 mmol/L of citral, aflT was completely inhibited, followed by aflM, aflP, aflR, and aflD with average of 257-, 29-, 3.5-, and 2.5-folds reduction, respectively. These results suggest that the reduction in AFB1 production by cinnamaldehyde, eugenol, and citral at low concentration may be due to the down-regulations of the transcription level of aflatoxin biosynthetic genes. Cinnamaldehyde and eugenol may be employed successfully as a good candidate in controlling of toxigenic fungi and subsequently contamination with aflatoxins in practice.

Daqu Fermentation Selects for Heat-Resistant Enterobacteriaceae and Bacilli

“…constitute a significant portion of the microbial population in Daqu (19,21,22); their endospores survive under low-moisture conditions and at high temperatures (35). This study demonstrated that the count of spores increased during fermentation; the taxonomic identification of spore-forming bacteria matched prior reports on Daqu microbiota (Tables 1 and 2) (22,36). More surprisingly, 50% of the isolates of sporeformers were spoVA 2mob positive.…”

Progress on the Antimicrobial Activity Research of Clove Oil and Eugenol in the Food Antisepsis Field

“…Eugenol (0.80 mM) expresses no effect on the growth of Aspergillus flavus , but completely inhibits the aflatoxin B1 (AF B1) biosynthesis production with a inhibition rate of 95.4%, and this function is associated with downregulating the transcription level of aflatoxin biosynthetic genes as aflR, aflT, aflD, aflM, and aflP, and among these genes, aflP is highly downregulated about 2061‐folds (Liang et al., ). In a molecular system composed of 60 genes including 27 aflatoxin B biosynthetic genes and 33 regulatory factors, the expression of almost all genes of this AFB₁ biosynthesis cluster are significantly inhibited by eugenol (0.5 mM), and this transcriptomic effect is associated with downregulating two internal regulatory factors AflR and AflS, and is also influenced by the overexpression of two genes veA and mtfA, which are directly linked to AFB₁ cluster regulation (Caceres et al., ).…”

Piperine inhibits aflatoxin B1 production in Aspergillus flavus by modulating fungal oxidative stress response

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